Field of the Invention
The present invention relates to an image forming apparatus, a method, and a storage medium storing a program for performing image formation processing.
Description of the Related Art
In image forming apparatuses, there are cases in which images are generated by switching a rendering method based on attribute information included in an inputted rendering command. Here, attribute information is information indicating a type of a rendering command, such as graphic, image, or text, for example.
Elements of a rendering object such as graphics, images, and text are rendered by processing called a scan conversion, and outputted to a raster output device. In a scan conversion, color values and positions of pixels, which are the smallest unit of an output device, are calculated from data in which elements of a rendering object are mathematically described, and an output image that is appropriate for the resolution of the output device is rendered.
There are cases in which various rendering methods are used when determining a color value of a pixel in accordance with a rendering command in the scan conversion. For rendering methods there are an intersect method, a top-left method, a center method and the like. In the intersect method, pixels that intersect even slightly with a rendering region of an object are filled in. In the top-left method, only pixels for which the top-left end point of the pixel are within an object rendering region are filled in. In the center method, only pixels for which the center of the pixel is within an object rendering region are filled in. Also, using rendering methods that differ depending on attribute information of a rendering object is well known. For example, the intersect method is used in rendering of an object having a graphic attribute, and the center method is used in rendering of an object having an image attribute.
Meanwhile, a technique of amending a thin line object and outputting in order to improve thin line reproducibility when rendering a thin line rendering object (thin line object) whose width is narrow. In Japanese Patent Laid-Open No. H4-139589 is recited a technique that improves thin line reproducibility by, if the width is 1 dot or less, executing anti-aliasing processing at a different gradation than usual. By improving thin line reproducibility in this way, it is possible to improve a print characteristic of an image forming apparatus. For example, by performing correction that widens a width of a thin line object, a thin line being outputted thinly is prevented.
A scan conversion of an object of the graphic attribute is executed by the intersect method in which pixels that intersect the object rendering region even slightly are filled in. In such a case, there are times when a width ends up being too wide depending on the position of the rendering object.